The study will use a registry approach to conduct active surveillance among children < 12 years of age at enrollment. Occurrences of abnormalities from ART exposure in utero and/or in the first two months of life will be sought in multiple domains, including metabolic, growth, cardiac, neurologic, neurodevelopmental, behavior, language, and hearing. Clinical and laboratory data will be examined for abnormalities through a hierarchy of evaluations: adverse events (AE) will be identified → selected AEs will trigger predefined additional evaluations → significant observations will be defined as cases → a pattern of significant study-wide cases will be defined as signals. The incidence of these events of interest will be monitored over time and by ART regimen, and compared with historical data that may be suggestive of a signal. Some signals may be testable using existing and/or previously collected data, while other signals may indicate the need for additional hypothesis-driven studies outside of SMARTT.